Coated optical substrates

ABSTRACT

Optical devices having multi-functional coatings.

This application draws priority from UK Patent Application No.1406200.4, filed Apr. 7, 2014 and entitled “COATED OPTICAL SUBSTRATES”,which application is hereby incorporated by reference, as if fullydisclosed herein.

FIELD OF THE INVENTION

The present invention relates to multi-functional coated opticalsubstrates and, more particularly, to optical devices in whichmicrometric functional areas form a multi-functional layer on an opticalsubstrate such as a lens.

SUMMARY OF THE INVENTION

According to some teachings of the present invention there is providedan optical device including: (a) an optical substrate; (b) at least onemulti-functional layer, fixedly attached to a broad surface of theoptical substrate; the multi-functional layer including a plurality ofmulti-functional areas, each area of the multi-functional areasincluding functional dots, each of the functional dots fractionallycovering the area; each area of the multi-functional areas having arectangular projection normally projecting from a direction of thelayer, onto the broad surface, the rectangular projection having acontiguous area of up to 0.04 square millimeters and a short side of atleast 20 micrometers; the functional dots including: a first group ofthe functional dots, having a first functionality; a second group of thefunctional dots, having a second functionality, the second functionalityhaving a differing functionality from the first functionality; wherein,within at least one area of the multi-functional areas, the first grouphas a characteristic height H1, the second group has a characteristicheight H2, the characteristic heights satisfying at least one of thefollowing relationships:

H2>k*H1  (1);

H2≥H1+k2  (2);

k being at least 1.05; k2 being at least 1 micrometer (μm).

According to another aspect of the present invention there is providedan optical device including: (a) an optical substrate; and (b) at leastone multi-functional layer, fixedly attached to the optical substrate;the multi-functional layer including a plurality of multi-functionalareas, each area of the multi-functional areas including functionaldots, each of the functional dots fractionally covering the area; eacharea of the multi-functional areas being a rectangular area having acontiguous area of up to 0.04 square millimeters and a short side of atleast 20 micrometers; the functional dots including: a first group ofthe functional dots, having a first functionality; and a second group ofthe functional dots, having a second functionality, the secondfunctionality having a differing functionality from the firstfunctionality.

According to yet another aspect of the present invention there isprovided an optical device including: (a) an optical substrate; and (b)at least one multi-functional layer, fixedly attached to the opticalsubstrate; the multi-functional layer including a plurality ofmulti-functional areas, each area of the multi-functional areasincluding functional dots, each of the functional dots fractionallycovering the area; each area of the multi-functional areas being arectangular area having a contiguous area of up to 0.04 squaremillimeters and a short side of at least 20 micrometers; the functionaldots including: a first group of the functional dots, having a firstfunctionality; a second group of the functional dots, having a secondfunctionality, the second functionality having a differing functionalityfrom the first functionality; wherein, within at least one area of theareas, the first group has a characteristic height H1, and wherein, atthe height H1, an upper characteristic diameter (D(H1)) of the secondgroup of the functional dots is at most equal to a lower characteristicdiameter (D(0)) of the second group of the functional dots at a lower orbase end thereof.

According to yet another aspect of the present invention there isprovided an optical device including: (a) an optical substrate; (b) atleast a first multi-functional layer, fixedly attached to the opticalsubstrate; and (c) at least a second multi-functional layer, fixedlyattached to the first multi-functional layer, the first multi-functionallayer disposed between the substrate and the second multi-functionallayer; each of the first and the second multi-functional layers having aplurality of multi-functional areas, each area of the multi-functionalareas including functional dots, each of the functional dotsfractionally covering the area; each area of the multi-functional areasbeing a rectangular area having a contiguous area of up to 0.04 squaremillimeters and a short side of at least 20 micrometers; the functionaldots including: a first group of the functional dots, having a firstfunctionality; a second group of the functional dots, having a secondfunctionality, the second functionality having a differing functionalityfrom the first functionality.

According to yet another aspect of the present invention there isprovided a method of producing a multi-functional coated opticalsubstrate by jetting or ink-jetting, substantially as described herein.

According to further features in the described preferred embodiments,the at least one group of functional dots (often the first group offunctional dots) includes a photochromic colorant.

According to still further features in the described preferredembodiments, the functional dots further include a third group of thefunctional dots having a third functionality, the third functionalityhaving a differing functionality with respect to the first and secondfunctionalities.

According to still further features in the described preferredembodiments, P represents a number of the groups of functional dots, andwherein a number of the groups of functional dots having thephotochromic colorant is at most (P−1).

According to still further features in the described preferredembodiments, P is at least 3, at least 4, or at least 5.

According to still further features in the described preferredembodiments, the photochromic colorant covers less than 70%, less than60%, less than 40%, or less than 20% of a total surface area of themulti-functional layer.

According to still further features in the described preferredembodiments, the second composition differs with respect to said firstcomposition.

According to still further features in the described preferredembodiments, the second functionality differs with respect to said firstfunctionality.

According to still further features in the described preferredembodiments, k2 is at least 1.5 μm, at least 2 μm, at least 3 μm, atleast 4 μm, or at least 5 μm.

According to still further features in the described preferredembodiments, the second group of functional dots has an anti-scratchfunctionality.

According to still further features in the described preferredembodiments, the multi-functional groups are selected from the groupconsisting of an anti-reflectant, an anti-scratch material; an anti-fogmaterial; and an ultraviolet (UV) absorber.

According to still further features in the described preferredembodiments, k is at least 1.10, at least 1.15, at least 1.20, at least1.30, at least 1.45, at least 1.60, at least 1.80, or at least 2.00.

According to still further features in the described preferredembodiments, k is at most 3.0, at most 2.6, at most 2.4, at most 2.2, orat most 2.1.

According to still further features in the described preferredembodiments, k is within a range of 1.07 to 2.8, 1.07 to 2.5, 1.07 to2.3, 1.07 to 2.0, 1.07 to 1.8, 1.07 to 1.7, 1.07 to 1.6, 1.07 to 1.5,1.07 to 1.4, 1.07 to 1.3, 1.15 to 1.8, 1.15 to 1.6, or 1.15 to 1.4.

According to still further features in the described preferredembodiments, the optical substrate is a curved optical substrate, andthe broad surface is a curved broad surface.

According to still further features in the described preferredembodiments, within each area of the multi-functional areas, a gapbetween adjacent functional dots belonging to the first and secondgroups, respectively, is at least 5 μm, at least 8 μm, at least 10 μm,at least 12 μm, at least 15 μm, or at least 20 μm.

According to still further features in the described preferredembodiments, the gap is at most 50 μm, at most 45 μm, at most 40 μm, atmost 35 μm, at most 30 μm, or at most 25 μm.

According to still further features in the described preferredembodiments, within each area of the multi-functional areas, a gapbetween adjacent functional dots belonging to the first and secondgroups, respectively, is at least 5 μm, at least 8 μm, or at least 10μm, and at most 100 μm, at most 50 μm, at most 45 μm, at most 40 μm, atmost 35 μm, at most 30 μm, or at most 25 μm, at most 20 μm, at most 18μm, or at most 15 μm.

According to still further features in the described preferredembodiments, within each area of said multi-functional areas, a gapbetween adjacent functional dots belonging to the first and secondgroups, respectively, is at most 100 μm, at most 50 μm, at most 45 μm,at most 40 μm, at most 35 μm, at most 30 μm, or at most 25 μm, at most20 μm, at most 18 μm, or at most 15 μm, the adjacent functional dotsbeing physically discrete.

According to still further features in the described preferredembodiments, the gap is an average gap of at least 10, at least 25, atleast 50, or at least 100 randomly selected multi-functional areas ofthe plurality of multi-functional areas.

According to still further features in the described preferredembodiments, the gap is an average gap between all pairs of the adjacentfunctional dots within an optical field of view image, the imagecontaining at least 10, at least 25, at least 50, or at least 100functional dots.

According to still further features in the described preferredembodiments, the functional dots are distributed over a nominal surfacearea, the functional dots having a total coverage area, a ratio of thetotal coverage area to the nominal surface area being at most 0.98, atmost 0.96, at most 0.94, at most 0.92, at most 0.90, at most 0.85, atmost 0.80, at most 0.75, at most 0.70, at most 0.65, at most 0.60, atmost 0.55, at most 0.50, at most 0.45, at most 0.40, or at most 0.35.

According to still further features in the described preferredembodiments, this ratio is at least 0.35, at least 0.40, at least 0.45,at least 0.50, or at least 0.55.

According to still further features in the described preferredembodiments, this ratio is within a range of 0.50 to 0.98, 0.50 to 0.90,0.55 to 0.90, 0.60 to 0.90 or 0.65 to 0.90.

According to still further features in the described preferredembodiments, the multi-functional layer is directly attached to theoptical substrate.

According to still further features in the described preferredembodiments, the multi-functional layer is separated from the opticalsubstrate by a distance of at most 1000 nm, at most 700 nm, at most 500nm, at most 300 nm, at most 200 nm, at most 150 nm, at most 120 nm, atmost 100 nm, at most 80 nm, at most 60 nm, or at most 40 nm. Accordingto still further features in the described preferred embodiments, theoptical substrate has a thickness of at least 0.5 mm, at least 1 mm, atleast 1.5 mm, at least 2 mm, at least 3 mm, at least 4 mm, at least 5mm, at least 6 mm, at least 8 mm, at least 10 mm, or at least 20 mm.

According to still further features in the described preferredembodiments, at least one group of the groups of functional dotsincludes at least one of a UV absorber, an anti-reflectant, ananti-scratch material, an impact resistance material, and an anti-fogmaterial.

The anti-scratch coatings produced may have a haze value of at most 5%,at most 4%, at most 2.5%, or at most 1%, and typically have a haze valueof at least 0.5% or at least 0.8%, using the ASTM D1004-08 describedhereinbelow.

According to still further features in the described preferredembodiments, the optical substrate is a lens.

According to still further features in the described preferredembodiments, the optical substrate is a thermoplastic optical substrateor a glass optical substrate.

According to still further features in the described preferredembodiments, the second multi-functional layer is directly attached tothe first multi-functional layer, or to an overcoat layer thereof.

According to still further features in the described preferredembodiments, the composition of at least one, at least two, or all ofthe groups of functional dots differs with respect to the composition ofsaid broad surface of said optical substrate.

According to still further features in the described preferredembodiments, at least one, at least two, or all of the groups offunctional dots include, mainly include, or consist of jetted dots.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice. Throughout thedrawings, like-referenced characters are used to designate likeelements.

In the drawings:

FIG. 1A is a schematic top perspective view of an optical substratehaving a multi-functional layer fixedly attached to a broad surfacethereof, according to embodiments of the present invention;

FIG. 1B is a schematic cross-sectional view of an optical substratehaving a multi-functional layer fixedly attached to a broad surfacethereof, according to embodiments of the present invention;

FIG. 2 provides a schematic cross-sectional view of an inventive opticalconstruction including an optical substrate having a multi-functionallayer affixed thereto, the multi-functional layer including functionaldots having different characteristic heights;

FIG. 3 is a schematic cross-sectional view of an inventive opticalconstruction including an optical substrate having a multi-functionallayer affixed thereto, the multi-functional layer including at leastthree arrays of functional ink dots;

FIG. 4 provides a schematic top view of the inventive opticalconstruction of FIG. 3;

FIG. 5 is a magnified, optical image of an optical constructionincluding an array of blue ink dots attached to an optical substrate;

FIG. 6 provides a magnified, optical image of the array of blue ink dotson an optical substrate, as in FIG. 5, to which substrate has beenfixedly added, in interdisposed fashion, an array of violet ink dots, inaccordance with the present invention;

FIG. 7 provides magnified, optical images of optical constructionshaving: (i) a field solely having blue ink dots; (ii) a field solelyhaving violet ink dots, and (iii) a field having both blue dots andviolet dots;

FIG. 8 plots absorption as a function of wavelength for the fieldsprovided in FIG. 7; and

FIG. 9 provides relative absorption plots for the fields provided inFIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principles and operation of the optical devices according to thepresent invention may be better understood with reference to thedrawings and the accompanying description.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Coated optical substrates often contain at least one photochromiccolorant. Such dyes typically change color—reversibly—in response toultraviolet light, usually typically turning clear in the absence ofsunlight or other source of ultraviolet light.

In this photochromic transition, the photochromic colorant undergoes areversible photochemical reaction in which an absorption band in thevisible part of the electromagnetic spectrum changes in strength orwavelength.

For practical use in optical coatings, the properties of thephotochromic material must satisfy numerous performance criteria,conditions and constraints, a non-exhaustive list of which includes:

-   -   providing a noticeable, major change in color;    -   rate of color change (both ways)    -   minimal residual color    -   thermal stability under ambient conditions for both states of        the photochromic colorant;    -   sufficient efficiency of the photochromic change with respect to        the amount of light absorbed (“quantum yield”);    -   minimal or sufficient non-overlapping of the active absorbance        bands of the two states;    -   long-term stability of the photochromic reversibility (“fatigue        resistance”). Photochromic materials become less reversible over        time, due to photodegradation, photooxidation, and other        processes;    -   provide a suitable environment accommodating the polarity of        each state, and the resultant differential in polarity.

There exist sundry technological challenges in producing coated opticalsubstrates, and more particularly, multi-functional coated opticalsubstrates having at least one photochromic ink or substance.

In producing coated optical substrates, technological challengesinclude:

-   -   the refractive index of the coating is constrained to be similar        to that of the optical substrate;    -   mechanical properties (e.g., abrasion scratch and impact        resistance, thermal stability): since optical elements may be        exposed to rough conditions in normal use; and    -   optical quality: clarity, no haze, no optical effects, no        defects, no color.

The technological challenges may also relate to various stringentperformance criteria for the coated optical device, such as the kineticsof the color change, residual color, uniformity of the color change, andthe physical and chemical durability of the coated optical device overthe long term.

In producing multi-functional coated optical substrates, thetechnological challenges and hurdles may relate to the peculiarities andspecial requirements of each photochromic ink, to the specialcharacteristics and requirements of the optical substrate, and to theintegration of this ink, along with the other inks or materialsproviding the multi-functionality, with the optical substrate.

The inventors have found that introducing a plurality of photochromicmaterials into a single inkjet formulation may appreciably compromisethe coating performance (including photochromic performance, mechanicalperformance, fatigue resistance). Each photochromic material may havesingular intrinsic kinetics with respect to the photochromic change.

Moreover, the constraints introduced by including such a plurality ofphotochromic materials into a single inkjet formulation may result inthe formulation being unsuitable for ink-jetting (e.g., excessiveviscosity or surface tension).

One aspect of the present invention pertains to a method of applying aplurality of formulations to an optical substrate. Another aspect of thepresent invention pertains to a multi-functional coated opticalsubstrate in which micrometric functional areas form at least onemulti-functional layer thereon. Various aspects of the present inventionpertain to specific structural features of such multi-functional coatedoptical substrates.

The inventors have found that applying a plurality of optical coatingsto an optical substrate involves a variety of technological hurdles.Some of these relate to optical substrates, which tend to be highlysmooth, and substantially non-absorbent. Optical substrates aregenerally transparent, and may require a high degree of transparencyfrom the plurality of optical coatings. Moreover, the refractive indexof each coating, or of all the coatings together, is constrained to besimilar to that of the optical substrate.

The plurality of optical coatings must satisfy mechanical criteria suchas hardness and/or scratch resistance. Each of the plurality of coatingsmust also be relatively inert to the other coatings in contacttherewith. Moreover, since the coatings may be applied successively, atleast one of the applied wet, or uncured, formulations may contact, andinteract with, a previously applied coating. This may be particularlyproblematic in the case of successive applications of differentphotochromic ink formulations.

The curing time of each coating should be reasonable (minutes or hours),and the minimum curing temperature should be sufficiently low so as notto damage the optical substrate, nor damage any previously appliedcoatings.

An inventive coated optical substrate may be prepared by printing twodifferent inks, each ink containing a different functional material(e.g., two photochromic dyes). In a first step, a first array of dropscontaining the first function (photochromic dye no. 1) is printed(ink-jetted) such that the distance between drops, measured from thecenter of a first drop to the center of the adjacently jetted drop, is100 micrometers (μ).

In order to control the viscosity at jetting, the printhead may beheated, e.g., to a temperature within a range of 30° C. to 60° C., or35° C. to 55° C. In order to control the spreading of the drops on theoptical substrate, the substrate may be heated to 30° C. to 60° C., 35°C. to 60° C., 40° C. to 60° C., or 45° C. to 60° C.

In a second step, a second array of drops containing the second function(photochromic dye no. 2) is printed (ink-jetted) between the drops ofthe first array of drops. The drops of the second function may beprinted under the same general conditions described above, but so as tobe placed at a particular, generally pre-defined distance from theadjacent drops of the first function, measured from the center of thefirst function drop to the center of the second function drop.

The drop characteristics may be optimized using a strobe.

Thermal curing is then performed, typically at 100° C. to 140° C.,typically for up to several hours.

The inventors have found that various functional ink-jet formulationstend to spread over the surface of the optical substrate, as describedhereinabove, which may compromise or severely impair precise positioningof jetted drops on the surface of optical substrate. Moreover, jetteddrops of different functionalities may bleed or coalesce. The inventorshave developed an anti-wetting formulation that is suitable forink-jetting, and that may largely inhibit this phenomenon.

The anti-wetting formulation is produced as follows: a mixture of 85%Dowanol™ PMA (propylene glycol methyl ether acetate) and 15% of Dowanol™TPM (tripropylene glycol methyl ether) is prepared. To this mixture areadded 20% BYK®340 (BYK Additives & Instruments) and 10% polyvinylbutyral (Mowital® B 20 H, Kuraray Co., Ltd., Japan), containing 18-21%polyvinyl alcohol and 1-4% polyvinyl acetate, based on the technicaldata sheet of the manufacturer. The resultant mixture may be stirred forabout an hour, followed by filtering with a PTFE syringe filter rated at1 micrometer (μm), having a diameter of 25 mm, and equipped with apolypropylene housing and a pre-filter. The anti-wetting formulation maythen be loaded in the inkjet printer cartridge.

In order to produce generally round ink dots that are substantially freeof spreading/bleeding and coalescing phenomena, the anti-wettingformulation may be deposited on the substrate prior to the printing ofthe functional inks. The anti-wetting formulation may be recorded solelyin or near the areas where the functional ink is to be printed, or as athin layer over an entire, continuous area of the substrate. Afterdrying, one or more functional inks may be printed over the dried dotsor areas of the anti-wetting layer or coating.

Using the anti-wetting formulation and the functional inks describedhereinbelow, the inventors have succeeded in printing interdisposed orinterlaced sets or arrays of functional ink dots on various opticalsubstrates, including flat glass substrates of various sizes, ophthalmiclenses of various shapes and materials, including glass, polycarbonateand CR-39 (or allyl diglycol carbonate—ADC). Moreover, although curvedoptical surfaces may appreciably exacerbate the spreading and bleedingphenomena, the inventors have succeeded in printing such interdisposedsets of functional ink dots on various optical substrates having suchcurved optical surfaces.

In order to control or shift the refractive index of the instantformulations and coatings, various nanoparticles such as TiO₂ and ZrO₂,having refractive indices of 1.6 to 1.8, may be added. It is essential,however, to get a stable non-aggregated dispersion of the particles inthe ink, with no agglomeration or sedimentation. In addition, the activeingredient (i.e., nano-particles) concentration should be adjusted andoptimized vs. viscosity and surface tension, such that the inkformulation remains suitable for jetting.

Another direction for controlling or shifting the refractive index ofthe instant formulations and coatings is to add to the formulation smallquantities of hard oligomers characterized by high refractive indices,such as poly(pentachlorophenyl methacrylate) or polyfunctional zirconiumand hafnium acrylate monomers having a refractive index above 1.6.

The formulations used to produce the optical devices and structures ofthe present invention may be tailored to be suitable for otherproperties of the optical substrate.

For example, surface energy adjustments may be made by introducingspecific surfactants (wetting agents) to the formulation, such asBYK®-333 (reduces surface tension). The chemical stability of thesurface may be adjusted by pre-coating for protection or by selecting asolvent that does not dissolve the substrate. Adhesion issues and needsmay be addressed by binders (different binders for different substrates,like PBB for glass or polycarbonate). Leveling agents (like BYK®-358)may be introduced to assure surface smoothness of the jetted drops andto avoid or appreciably reduce the phenomenon of “coffee rings”.

FIG. 1A is a schematic top perspective view of an exemplary inventiveoptical construction or device 100 produced by the inventive method.Optical construction 100 includes an optical substrate 20 such as alens, and a multi-functional layer 50 (better shown in FIG. 1B) fixedlyattached and adhering to a broad, optical surface 22 of opticalsubstrate 20. Multi-functional layer 50 includes a plurality ofmulti-functional areas 15, each of which being contained by a respectiverectangular projection 10 (i.e., an imaginary rectangular projection)normally projecting from a direction of the layer, onto surface 22. Eachrectangular projection is quite small, having a contiguous area of up to0.04 square millimeters. A short side of rectangular projection 10 has alength (W) of at least 20 micrometers.

Each of multi-functional areas 15 includes a first group of functionaldots such as functional dots 60, having a first composition and having afirst functionality, and at least a second group of functional dots suchas functional dots 80, having a second composition and having a secondfunctionality. As will be elaborated hereinbelow, the secondfunctionality may differ with respect to the first functionality, andthe second composition may differ with respect to the first composition.In the exemplary structure provided in FIGS. 1A and 1B, functional dots60 and functional dots 80 are interdisposed (or alternately disposed).

A schematic, partial cross-sectional view of the optical construction100 of FIG. 1A is provided in FIG. 1B, in which is shown a portion of amulti-functional area 15 attached to optical substrate 20. The portionof multi-functional area 15 shown includes a plurality of functionaldots 60, 80, each fractionally covering multi-functional area 15.

Typically, each of the at least first and second functionalities isselected from the group consisting of an anti-reflectance functionality,anti-scratch functionality; anti-fog functionality; ultraviolet (UV)absorber functionality; and photochromic functionality.

In some embodiments, the plurality of first functional dots 60 has acharacteristic or average height H1. At characteristic height H1, anupper characteristic length, upper characteristic diameter D(H1), orupper characteristic cross-sectional area of the second group of thefunctional dots is at most equal to a lower characteristic length, lowercharacteristic diameter D(0), or lower characteristic cross-sectionalarea of the second group of the functional dots at a lower or base endthereof, i.e., at the height of surface 22, at the interface betweensurface 22 and functional dots 80.

In some embodiments, a baseline gap L(0) or an average baseline gapbetween adjacent functional dots 60, 80 having different functionality,may be at least 5 μm, at least 8 μm, at least 10 μm, at least 12 μm, atleast 15 μm, or at least 20 μm. The baseline gap is measured at thebottom of the functional dots, as shown.

In some embodiments, a peak gap L(H1) or an average peak gap betweenadjacent functional dots 60, 80 having different functionality, may beat least 12 μm, at least 15 μm, at least 20 μm, at least 30 μm, or atleast 40 μm. The peak gap is measured at the top of the functional dots.When the second group of dots has a higher characteristic height thanthe characteristic height (H1) of the first as shown, and is measuredsubstantially parallel to the top surface 22 of optical substrate 20.

In some embodiments, peak gap L(H1) or the average peak gap may exceedbaseline gap L(0) or the average baseline gap by at least 6 μm, at least8 μm, at least 10 μm, at least 12 μm, at least 15 μm, or at least 20 μm.

FIG. 2 is a schematic cross-sectional view of an inventive opticalconstruction or device 200 including an optical substrate 20 having amulti-functional layer 250 affixed thereto. Multi-functional layer 250includes a first group or set of functional dots such as firstfunctional dots 230, having a first composition and having a firstfunctionality, and at least a second group or set of functional dotssuch as second functional dots 260, having a second composition andhaving a second functionality. In FIG. 2, the second functional dots 260are disposed between the first functional dots 230 (or the first andsecond functional dots are “interdisposed”. In the exemplary structureprovided in FIG. 2, the first set of functional dots 230 and the secondset of functional dots 260 have differing characteristic heights (H1 andH2, respectively). These characteristic heights may fulfill thefollowing relationship:

H2>k*H1,

wherein k is a constant having a value of at least 1.05. In someembodiments, k is at least 1.10, at least 1.15, at least 1.20, at least1.30, at least 1.45, at least 1.60, at least 1.80, or at least 2.00.

In some embodiments, k is at most 3.0, at most 2.6, at most 2.4, at most2.2, or at most 2.1.

For adjacent dots, or for an average between adjacent dots, H2 mayexceed H1 by at least 1.0 μm, at least 1.5 μm, at least 2.0 μm, at least3 μm, at least 4 μm, or at least 5 μm. Typically, H2 may exceed H1 by atmost 10 μm, at most 8 μm, or at most 6 μm.

The inventors have found that by having second set of functional dots260 protrude above first set of functional dots 230, second set offunctional dots 260 may protect first set of functional dots 230 fromvarious kinds of mechanical damage or trauma, including scratching andrubbing operations.

By way of example, first set of functional dots 230 may advantageouslycontain, primarily contain, or consist essentially of, a firstphotochromic material.

By way of example, second set of functional dots 260 may advantageouslyinclude, primarily include, or consist essentially of an anti-scratchformulation or material.

In some embodiments, multi-functional layer 250 may further include athird set of functional dots 240 having a characteristic height 113. Byway of example, third set of functional dots 240 may advantageouslyinclude, primarily include, or consist essentially of, (i) a firstphotochromic material or ink dot; (ii) a dot produced from an anti-glareformulation; (iii) a dot produced from an anti-fog formulation; (iv) adot produced from an anti-reflection formulation; (v) a dot producedfrom a UV-absorbing formulation; (vi) a dot produced from ananti-scratch formulation (including an abrasion resistance, impactresistance, and/or scratch resistance formulation); or a dot producedfrom a dye/colorant formulation providing a fixed tint.

In some embodiments, multi-functional layer 250 may further include aplurality of a fourth set of functional dots 270 having a characteristicheight 114.

These characteristic heights may fulfill the following relationship:

H4>k*H3.

Additionally or alternatively, these characteristic heights may fulfillat least one of the following relationships:

H2>k*H3;

H4>k*H1.

By way of example, third set of functional dots 240 may advantageouslycontain, primarily contain, or consist essentially of, a secondphotochromic material.

By way of example, fourth set of functional dots 270 may advantageouslyinclude, primarily include, or consist essentially of an anti-scratchformulation or material, an anti-glare formulation or material, or aUV-absorbing formulation.

In some embodiments, at least two, at least three, or at least four ofthe sets of functional dots 230, 240, 260, 270 are photochromic dots.

Third set of functional dots 240 may be disposed so as to bemechanically protected by second set of functional dots 260 and/or byfourth set of functional dots 270.

The characteristic differential in dot heights between different sets offunctional dots may be achieved in various ways. For example, when onlyone drop-volume is possible, the formulation of the ink may be changedto promote or to inhibit spreading of the drop.

The parameters of the ink that may affect the height include:

-   -   Inhibiting the spreading of the drop can be achieved by:        -   changing the rheology of the ink using rheology modifier            that produces thixotropy;        -   expediting drying by using a high evaporation-rate solvent            or co-solvent and/or heating the substrate;        -   treating the surface of the substrate to change the surface            tension of the substrate.    -   Promoting the spreading by:        -   reducing the viscosity (by using a different solvent or            surfactant);        -   increasing wetting using wetting agents or applying surface            treatment (chemical or physical).

In another approach, drop volume may be controlled (increased ordecreased) by using a print head that has a gray scale feature such asthe XAAR head (1001 GS6). The gray scale feature allows variable sizeddrops of ink to be deposited directly on the substrate. Thus, by bothincreasing the volume of the drop and preventing spreading (as describedin the previous approach), the height differential may be achieved.

In another approach, drop approach, drop height may be varied, for agiven drop volume, by formulating inks having different solidsconcentrations. This is exemplified in Examples 36-38 hereinbelow.

FIG. 3 is a schematic cross-sectional view of an exemplary inventiveoptical construction or device 300 including an optical substrate 20having a multi-functional layer 350 affixed thereto. Multi-functionallayer 350 includes a plurality of multi-functional areas, each includinga plurality of first, second, and third functional dots, such asfunctional dots 330, 360, and 340, the plurality of first, second, andthird functional dots being interdisposed. This is further evident fromFIG. 4, which provides a schematic top view of inventive opticalconstruction 300.

With reference again to FIG. 3, multi-functional layer 350 may becovered or at least partially covered by an overcoat layer 380, whichmay be applied, by way of example, by an inkjet printer operating inlayer mode. Other methods of application will be evident to those ofskill in the art. Overcoat layer 380 is typically applied aftermulti-functional layer 350 has been cured.

In some embodiments, an additional functional or more typically, anadditional multi-functional layer, may be disposed on top ofmulti-functional layer 350, either directly, or on top of overcoat layer380, as shown. The additional multi-functional layer may be similar tomulti-functional layer 350, including a plurality of multi-functionalareas, each having a plurality of functional dots, such as functionaldots 385 and 390. This additional multi-functional layer may be coveredby an overcoat layer (not shown) that may be substantially similar toovercoat layer 380.

Each functional dot of the additional multi-functional layer may bedisposed at least partially above (e.g., functional dot 385) or fullyabove a functional dot in multi-functional layer 350. In someembodiments, functional dots of the additional multi-functional layermay be disposed such that functional dots in multi-functional layer 350do not even partially intercede between functional dots of theadditional multi-functional layer and optical substrate 20. The term“above” is with respect to a line extending normally upward in thedirection of multi-functional layer 350.

Referring again to FIG. 4, a multi-functional layer 350 adhering tooptical substrate 20 includes a plurality of multi-functional areas 415,each of which is contained by a respective rectangular projection 410(i.e., an imaginary rectangular projection) normally projecting from adirection of the multi-functional layer, onto the upper surface ofoptical substrate 20, and substantially as described hereinabove.

EXAMPLES

Reference is now made to the following examples, which together with theabove description, illustrate the invention in a non-limiting fashion.

Materials and Equipment

BYK®-333 (ALTANA AG): a silicone-containing surface additive forsolvent-free, solvent-borne and aqueous coating systems, printing inksand adhesive systems as well as ambient-curing plastic systems; adaptedto strongly reduce surface tension.

BYK®-358 N (ALTANA AG): a surface additive on polyacrylate-basis forsolvent-borne coating systems and printing inks; a standard levelingadditive; adapted to add no turbidity in clear coats and no haze inpigmented systems.

PH-1209 (Chromtech Ltd 2 Bergman Street, Rabin Park 76705 RehovotIsrael): a pale yellow (or slightly rose) powder; an aryl substitutedheterocyclic photochromic dyestuff; melting point of 180-181° C.

PH-2228 (Chromtech Ltd): a yellow photochromic powder; an arylsubstituted heterocyclic photochromic dyestuff; melting point of171-173° C.

465 (Chromtech Ltd): a yellow or pale bluish powder, an aryl substitutedheterocyclic photochromic dyestuff; melting point of 139-140° C.

4114 (Chromtech Ltd); a pale-yellow greenish photochromic powder; anaryl substituted heterocyclic photochromic dyestuff; melting point of166-167° C.

6121F-80 (Eternal Chemical Co.): an aromatic urethane diacrylate dilutedin 20% DPGDA.

X-10 (HCS Korea, 715, Jungwoo Venture Town II, 1228-1 Shingil-Dong,Danwon-Gu, Ansan-City Kyunggi-Do, Korea): transparent, temperaturecurable coating material containing, by weight, 30-40% copolyesterresin, 20-30% water, and 20-30% silica sol.

Dowanol™ PMA Glycol Ether (Propylene glycol monomethyl ether acetate, orPMA) (Dow Chemical Company Ltd). Characteristic physical properties ofthe Dowanol™ PMA are:

Property Value Molecular Weight (g/mol) 132.2 Boiling Point @ 760 mmHg,1.01 ar 146° C. (295° F.) Flash Point (Setaflash Closed Cup 45.5° C.(113.9° F.) Freezing Point −66° C. (−87° F.) Vapor pressure@ 20° C. -extrapolated  2.8 mmHg 355 Pa Specific gravity (20/20° C.) 0.964 LiquidDensity @ 20° C. 0.967 g/cm3 @ 25° C. 0.963 g/cm3 Vapor Density (air= 1) 4.6 Viscosity (cP or mPa · s @ 25° C.) 1.1 Surface tension(dynes/cm or mN/m @ 20° C.) 26.9 Specific heat (J/g/° C. @ 25° C.) 1.85Heat of vaporization (J/g) at normal boiling 296 point

Dowanol™ TPM Glycol Ether (Tripropylene glycol monomethyl ether, or TPM)(Dow Chemical Company Ltd). Characteristic physical properties of theDowanol™ TPM are:

Molecular weight (g/mol) 206.3 Boiling point @ 760 mmHg, 469° F. 243° C.1.01 bar Flash point (Closed Cup) 250° F. 121° C. Freezing point −108°F. −78° C. Vapor pressure ® 20° C. - 0.01 mmHg extrapolated 0.02 mbarSpecific gravity (25/25° C.) 0.965 Density @ 20° C. 8.06 lb/gal 0.966g/cm³ @ 25° C. 8.03 lb/gal 0.962 g/cm³ Viscosity (cP or mPa · s 5.5 @25° C.) Surface tension (dynes/cm or 30.0 mN/m @ 25° C.) Specific heat(J/g/° C. 2.12 @ 25° C.) Heat of vaporization (J/g) at 210 normalboiling point Net heat of combustion (kJ/g) - 27.8 predicted @ 25° C.Autoignition temperature 531° F. 277° C. Evaporation rate (n-butylacetate = 1.0) 0.0026 (diethyl ether = 1.0) >1200 Solubility, g/100 g @25° C. Solvent in water — Water in solvent — Hansen solubilityparameters (J/cm³)^(1/2) _d (Dispersion) 15.1 _p (Polar) 3.5 _h(Hydrogen bonding) 11.5 Flammable limits (vol. % in air) Lower 0.7 Upper14.8

Cymel® 370 (Supplier: Allnex): a fast-curing crosslinking agentincluding a partially methylated melamine monomer (50% by weight) iniso-butanol. The material does not require a strong acid catalyst.

Duroftal® 6117 VPE (Supplier: Allnex): a solvent-borne hydroxylatedpolyester flexibilizer for amino resin crosslinking, and having a Tg ofabout −55° C. S-24-25 Coating (EXXENE®, Corpus Christi, Tex.): aprimerless abrasion resistance silicone hard coating for applicationupon polycarbonate and ophthalmic substrates, the coating is a clearliquid sol-gel solution, curable via thermal curing. Characteristicphysical properties are:

Main Component Organic modified Silicone Appearance Clear LiquidViscosity@25° C.(cP) 25-28 Density@25° C. 0.93 Solids Level (%) 24~26 pH4~5

CN2300 (Sartomer): a high functionality, fast-curing, high molecularweight polyester acrylate oligomer having a (low) viscosity of 600 cpsat 25° C., an acrylate equivalent weight of 175, a Tg (by DMA) of 96°C., and a surface tension of 32 dynes/cm.

SR1135: (Sartomer): a photoinitiator—blend of phosphine oxide,trimethylbenzophenone, methylbenzophenone, oligo phenyl propanones.

Irgacure® 2022 (BASF): a liquid photoinitiator blend used to initiateradical polymerization of unsaturated resins after UV light exposure;may be used in pigmented formulations of all colors for curing of thicksections or for UV-stabilized clear coatings.

6103 (Eternal Chem. Co.): aliphatic urethane hexaacrylate, ahexafunctional, clean and clear oligomer.

Nanobyk® 3605: nanoparticle dispersion surface-treated silicananoparticles.

Silixan A120 (Silixan Gmbh, Saarbruecken-Guedingen, Germany): UVprotection additive solution, 20% solids—hindered amine light stabilizer(HALS) in 1-methoxy-2-propanol.

Print head—Fujifilm Dimatix™ Materials Printer 10 PL model#DMCLCP—11610/PN 700-11670-01 (Fujifilm Dimatix Inc.).

Printer—OmniJet 100 (Unij et Co. Ltd, Kyungki-do 462-807 Korea).

Exposure of samples to ultraviolet (UV) light was performed using a UVlamp.

Olympus® BX51 Fluorescence Microscope, for capture of optical images.

Spectrophotometric measurements were performed using a Cary 5000Spectrophotometer, Version 1.12 (Varian Inc.).

Example 1

64.48 grams of X-10 resin solution were mixed with 33.98 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye PH-1209(Chromtech, Ltd.) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 2

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye PH-1209(Chromtech, Ltd.) and 0.2 grams of the surfactant BYK®-333 were added tothe diluted resin, while mixing was continued for another 20 minutes.

Example 3

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye PH-1209 (Chromtech, Ltd.) and 0.2 grams of the surfactantBYK®-333 were added to the diluted resin, while mixing was continued foranother 20 minutes.

Example 4

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye PH-1209 (Chromtech, Ltd.) and 0.2 grams of surfactant (0.05 gramsBYK®-333 and 0.15 grams BYK®-358N) were added to the diluted resin,while mixing was continued for another 20 minutes.

Example 5

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye PH-1209(Chromtech, Ltd.) and 0.2 grams of surfactant (0.05 grams BYK®-333 and0.15 grams BYK®-358N) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 6

64.48 grams of the resin solution were mixed with 33.98 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye PH-2228(Chromtech, Ltd.) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 7

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye PH-2228(Chromtech, Ltd.) and 0.2 grams of the surfactant BYK®-333 were added tothe diluted resin, while mixing was continued for another 20 minutes.

Example 8

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye PH-2228 (Chromtech, Ltd.) and 0.2 grams of the surfactantBYK®-333 were added to the diluted resin, while mixing was continued foranother 20 minutes.

Example 9

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye PH-2228 (Chromtech, Ltd.) and 0.2 grams of surfactant (0.05 gramsBYK®-333 and 0.15 grams BYK®-358N) were added to the diluted resin,while mixing was continued for another 20 minutes.

Example 10

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye PH-2228(Chromtech, Ltd.) and 0.2 grams of surfactant (0.05 grams BYK®-333 and0.15 grams BYK®-358N) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 11

64.48 grams of the resin solution were mixed with 33.98 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye no. 465(Chromtech, Ltd.) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 12

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye no. 465(Chromtech, Ltd.) and 0.2 grams of the surfactant BYK®-333 were added tothe diluted resin, while mixing was continued for another 20 minutes.

Example 13

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye no. 465 (Chromtech, Ltd.) and 0.2 grams of the surfactantBYK®-333 were added to the diluted resin, while mixing was continued foranother 20 minutes.

Example 14

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye no. 465 (Chromtech, Ltd.) and 0.2 grams of surfactant (0.05 gramsBYK®-333 and 0.15 grams BYK®-358N) were added to the diluted resin,while mixing was continued for another 20 minutes.

Example 15

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye no. 465(Chromtech, Ltd.) and 0.2 grams of surfactant (0.05 grams BYK®-333 and0.15 grams BYK®-358N) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 16

64.48 grams of the resin solution were mixed with 33.98 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye no. 4114(Chromtech, Ltd.) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 17

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye no. 4114(Chromtech, Ltd.) and 0.2 grams of the surfactant BYK®-333 were added tothe diluted resin, while mixing was continued for another 20 minutes.

Example 18

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye no. 4114 (Chromtech, Ltd.) and 0.2 grams of the surfactantBYK®-333 were added to the diluted resin, while mixing was continued foranother 20 minutes.

Example 19

64.48 grams of the resin solution were mixed with 28.71 grams of PMA and5.07 grams of TPM solvents in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 1.54 gramsof dye no. 4114 (Chromtech, Ltd.) and 0.2 grams of surfactant (0.05grams BYK®-333 and 0.15 grams BYK®-358N) were added to the dilutedresin, while mixing was continued for another 20 minutes.

Example 20

64.48 grams of the resin solution were mixed with 33.78 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 1.54 grams of dye no. 4114(Chromtech, Ltd.) and 0.2 grams of surfactant (0.05 grams BYK®-333 and0.15 grams BYK®-358N) were added to the diluted resin, while mixing wascontinued for another 20 minutes.

Example 21 Printing Test

The printing test was performed using an Inkjet printer (FujifilmDimatix™ Materials Printer DMP-2831). A sample having dual functionalitywas prepared by printing two different inks, each ink containing adifferent photochromic dye. The sample was prepared in a two-stepprocess in which an array of drops containing the first function (dye 1)was printed at a distance of 100 micrometer from each other, measuredfrom the center of a first drop to the center of the adjacently jetteddrop. In order to control the viscosity at jetting and the spreading ofthe drops, the printhead was heated to 40° C. and the substrate washeated to 40° C.

The second function was added to the layer by jetting drops of thesecond ink containing the second function between the drops of the firstarray of drops. The drops of the second function were printed at thesame general conditions described above, but were jetted so as to beplaced at a distance of 50 micrometers between the drops of the firstfunction to the drops of the second function, measured from the centerof the first function drop to the center of the second function drop.

Example 22 Printing Procedure

Printing was performed on an OmniJet 100 (Unijet), using a Dimatix™print head (Fujifilm Dimatix™ 10 PL model #DMCLCP—11610/PN700-11670-01). The ink was filtered using syringe filters (1micrometer). The print head was pre-heated to 40° C. The dropcharacteristics were then optimized using a stroboscope mounted on theprinter (camera and light source synchronized with the jettingfrequency). The waveform was optimized for the ink, jetted at afrequency of 1500 Hz. After jetting, a drop size of about 50 micrometer(on the substrate) was achieved.

The first photochromic ink was printed on a glass slide, such that thedistance between drops was about 140 micrometers. This distance enabledthe deposition of the second ink drops in-between the drops of the firstink.

A second print head was used for jetting the second ink, usingessentially the identical printing parameters. The printing wasperformed using a 70 micrometer offset, such that each of the second setof ink drops was disposed in-between the first ink drops. Thermal curingwas then performed at 120° C. for 60 minutes.

Example 23

The procedure of Example 22 was performed using a first, blue ink,prepared according to Example 14 and a second, yellow ink, preparedaccording to Example 7.

Example 24

The procedure of Example 22 was performed using a first, blue inkprepared according to Example 14 and a second, red ink, preparedaccording to Example 3.

Example 25

The procedure of Example 22 was performed using a first, blue ink,prepared according to Example 14, and a second, violet ink, preparedaccording to Example 20. A magnified, optical image of the first set ofblue ink drops is provided in FIG. 5. FIG. 6 provides a magnified,optical image of the array of blue ink dots on an optical substrate, asin FIG. 5, to which substrate has been fixedly added, in interdisposedor interlaced fashion, an array of violet ink dots, in accordance withthe present invention.

Example 26

The blue ink of Example 25 was inkjetted on a first glass slide toproduce a blue ink area; the violet ink of Example 25 was inkjetted on asecond glass slide to produce a violet ink area; these blue and violetinks were then inkjetted onto the first glass slide according to theprocedure of Example 22, to form an area containing interlaced(interdisposed) blue and violet photochromic ink dots.

The slides were illuminated with UV light for 2 minutes using a UV lampprior to the images being captured.

Magnified, optical images showing the three fields of dots are providedin FIG. 7. Referring now to the top slide, the field of blue and violetdots is situated to the left of the field of blue dots. It will beappreciated that the field of blue dots appears relatively faint. In thebottom slide, the field of violet dots may be seen.

It is visible to the naked eye that the area with field of blue andviolet dots has a different shade than the fields containing solelyviolet dots or solely blue dots.

Example 27 Spectrophotometric Measurements

The printed samples of Example 25 were exposed to ultraviolet (UV) lightfor 2 minutes using a UV lamp, and were then placed in thespectrophotometer (Cary 5000, Version 1.12 (Varian Inc.)) formeasurement. FIG. 8 plots absorption as a function of wavelength (“WL”,in nm) for a field or area solely having the blue ink, for an areasolely having the violet ink, and for an area having both blue andviolet dots (as described in Example 26).

For each of these fields, maximum absorption occurred at the followingwavelengths:

blue field: 611 nm;

violet field: 579 nm

blue and violet field: 585 nm.

Each of the three absorption plots may be normalized by dividing all theabsorption values of a particular field by the maximum absorption valueof that field, such that the maximum absorption value for each fieldis 1. The relative absorption plots obtained are provided in FIG. 9.

Example 28

An anti-scratch inkjet formulation that may be particularly suitable foruse in conjunction with the invention has the following composition:

6121F-80: 20%

CN2300: 10%

SR1135: 5%

Irgacure® 2022: 2%

6103: 5%

Nanobyk® 3605: 5%

Dowanol™ PMA: 60%

The anti-scratch formulation is UV-curable, and has a characteristicsurface tension and a characteristic viscosity suitable for inkjet inks.The dried dots or layer produced from this formulation exhibit improvedabrasion resistance and impact resistance, relative to dried dots andlayer of the same composition, but devoid of the silica nanoparticles(Nanobyk® 3605). Moreover, the combination of resins utilized in theformulation themselves contribute to the anti-scratch, abrasionresistance and impact resistance properties.

Example 29

A UV-absorbing inkjet formulation that may be particularly suitable forproducing a coated optical substrate in conjunction with the inventionhas the following composition:

6121F-80: 20%

CN2300: 10%

SR1135: 5%

Silixan A120: 5%

Irgacure® 2022 2%

6103: 5%

Nanobyk® 3605 5%

Dowanol™ PMA: 55%

The formulation is UV-curable, and has a characteristic surface tensionand a characteristic viscosity suitable for inkjet inks.

Example 30

The glass transition temperature (Tg) of cured resins was determinedusing differential scanning calorimetry (DSC). A temperature curablecoating material (X-10), a solvent (Dowanol™ PMA) and optionally, acrosslinking formulation (Cymel 370) and/or a flexibilizing formulation(Duroftal® 6117 VPE) were weighed out on an analytical balance, toobtain a total weight of 10 grams. After shaking for 2 minutes to obtaina clear, homogeneous solution, 1 ml of the solution was deposited on aglass microscope slide and left to dry at 35° C. over a hot plate for 10hours. Each sample was cured by heating in an oven at 120° C. for 2hours to produce a cured coating. The cured layer was detached from themicroscope slide using a scalpel, and 0.5 grams of polymer wereintroduced into the DSC chamber.

Example 31

Differential scanning calorimetry runs were performed using a DSC823e(Mettler Toledo AG), in a six-phase procedure. Air is delivered to thechamber at a constant rate. After the sample has been introduced to theDSC chamber, the temperature is maintained for 5 minutes at −10° C.(Phase I). The temperature is then ramped up from −10° C. to 120° C. ata rate of 20° C./min. (Phase II). The temperature is held at 120° C. for3 minutes (Phase III), after which the temperature is ramped down from120° C. to −10° C. at a rate of 20° C./min. (Phase IV). The temperatureis held constant for 10 minutes. (Phase V). Finally, the temperature isramped back up from −10° C. to 120° C. at a rate of 20° C./min. (PhaseVI).

Examples 32-35

DSC runs were performed on the following compositions (all figures inweight-%), which were prepared according to Example 30. The DSC runswere performed according to the procedure provided in Example 31.

Component Example 32 Example 33 Example 34 Example 35 X-10 65 61.5 61.561.5 Cymel ® 370 — 3.5 — 1.75 Duroftal ® — — 3.5 1.75 6117 VPE Dowanol ™35 35 35 35 PMAFrom the DSC curves, the Tg of each of the cured resins was determined,as follows:

Tg (° C.) Example 32 56.22 Example 33 57.11 Example 34 55.41 Example 3556.31

All of the formulations in Examples 32-35 were found to be suitable foruse in the coated optical substrates of the present invention. Moreover,the results demonstrate how to modify the formulation so as to changethe Tg, and how to modify the properties of the formulation whilemaintaining, or controlling, the Tg. By way of example, with referenceto Example 32, Example 33 exhibits a small increase in Tg, due to theaddition of the (Cymel® 370) crosslinking agent. The opposite effect isachieved by adding a small quantity of the (Duroftal® 6117 VPE)flexibilizing agent: with respect to Example 32, the Tg is reduced. TheTg may be controlled or maintained by adding suitable quantities of boththe crosslinking and flexibilizing agents, as demonstrated by Example35. It will be appreciated by those of ordinary skill in the art thatfurther modifications in the Tg and/or in the physical characteristicsof the cured material may be engineered using this materials designapproach.

Example 36

3.00 grams of X-10 resin solution were mixed with 35.5 grams of PMAsolvent, 15.40 grams of TPM, 46 gr of Dowanol® PPh (Propylene glycolphenyl ether, CAS#770-35-4) in a 200 ml glass beaker equipped with amagnetic stirrer. After mixing the components for 10 minutes, 0.10 gramsof dye PH-1209 (Chromtech, Ltd.) were added to the diluted resin, whilemixing was continued for another 20 minutes to produce the ink.

Example 37

78.43 grams of the resin solution were mixed with 19.43 grams of PMAsolvent in a 200 ml glass beaker equipped with a magnetic stirrer. Aftermixing the components for 10 minutes, 2.00 grams of dye PH-1209(Chromtech, Ltd.) and 0.14 grams of the surfactant BYK®-333 were addedto the diluted resin, while mixing was continued for another 20 minutes.

Example 38

The inks from Examples 36 and 37 were inkjetted (˜6 picoliter drops) ona glass slide and cured, as described hereinabove, to produce severalhundred photochromic ink dots. The solids content of the inks was about50% and 1%, respectively. The ink dots of Example 36 had acharacteristic diameter of approximately 50 micrometers, and acharacteristic height of approximately 6.5 micrometers. The ink dots ofExample 37 had a characteristic diameter of approximately 50micrometers, and a characteristic height of approximately 0.9micrometers. Both results correlate well with the calculated heights,based upon the solids concentrations of the inks.

Examples 39-40

70 grams of the resin solution were mixed with 28 grams of PMA solventin a 200 ml glass beaker equipped with a magnetic stirrer. After mixingthe components for 10 minutes, 2 grams of dye C250-483 Opti-Safe LensDye Packet, RASPBERRY (Phantom Research Laboratories, Inc.) were addedto the diluted resin (Example 39) and BLACK (Example 40). Mixing wascontinued for another 20 minutes to produce the respective fixed tintcolorant inks.

Field of View

Using a more robust, statistical approach, however, may betterdistinguish between the inventive coated optical substrates and thecoated optical substrates known in the art. Thus, in some embodiments ofthe present invention, the coated optical substrate may be characterizedas at least first and second pluralities of ink dots interdisposed orinterlaced on the optical substrate, within a representative “field ofview”, the first and second pluralities of dots being made of differentcompositions and exhibiting differing functionalities. Assuming thecharacterization of the dot is obtained through image processing, a“field of view” contains a plurality of dot images, of which at least 10dot images are suitable for image processing. Both the field of view andthe dot images selected for analysis are preferably representative ofthe total population of ink dots on the substrate (e.g., in terms of dotshape).

In the field of view procedure, a printed sample, preferably containinga high incidence of single ink dots, is scanned manually on the LEXTmicroscope, using a X20 magnification to obtain a field that includes atleast 10 single dots in a single frame. Care should be taken to select afield whose ink dot quality is fairly representative of the overall inkdot quality of the printed sample.

Each dot within the selected frame is analyzed separately. Dots that are“cleaved” by the frame margins (which may be considered a square orrectangular geometric projection) are considered to be outside of theframe, and are not analyzed. Any satellites are excluded from theanalysis. A “satellite” is defined as an ink dot whose area is less than25% of the average dot area of the dots within the frame, for frameshaving a generally homogeneous dot size, or as an ink dot whose area isless than 25% of the nearest adjacent dot, for non-homogeneous frames.

Each distinct ink dot is subsequently magnified with a X100 zoom, andimage processing may be effected according to the procedure providedherein/procedures known to those of skill in the art.

As used herein in the specification and in the claims section thatfollows, the term “percent”, or “%”, refers to percent by weight, unlessspecifically indicated otherwise.

As used herein in the specification and in the claims section thatfollows, the terms “anti-glare”, “anti-reflectance”; “anti-fog”;“ultraviolet absorber”; “photochromic”, and the like, unless otherwisespecified, are meant as used in the art of optical substrate coatings.

As used herein in the specification and in the claims section thatfollows, the term “anti-scratch”, with respect to a material such as aformulation or a coating, refers to a material whose dried and curedcoating exhibits a haze value of less than 6%, using the following taberabrasion properties, according to ASTM D1004-08 (CS 10 F wheel, 500 gLoad, 500 cycles).

Similarly, the term “ratio”, as used herein in the specification and inthe claims section that follows, refers to a weight ratio, unlessspecifically indicated otherwise.

As used herein in the specification and in the claims section thatfollows, the term “multi-functional area”, refers to an area containedby a rectangular projection normally projecting from a direction of thelayer, onto the broad surface, the rectangular projection having acontiguous area of up to 0.04 square millimeters and a short side of atleast 20 micrometers.

As used herein in the specification and in the claims section thatfollows, the term “characteristic”, with respect to a dot dimension suchas height, length or diameter, refers to the maximal value of that dotdimension. By way of example, for a square dot, 30 micrometers on aside, the characteristic diameter would be the diagonal, i.e., 30√2=42.4micrometers. For a dot having some peaks and crannies on the topsurface, distal to the optical substrate, the dot height would be themaximum height measured normal to the top surface of the substrate. Fora plurality of dots, the characteristic dimension is the average of thecharacteristic dimension of the individual dots within the plurality.

As used herein in the specification and in the claims section thatfollows, the term “average”, with respect to a dimension such as theheight, length or diameter of a plurality of dots, refers to thearithmetic mean of that dimension, and is calculated using thecharacteristic dimension for each dot in the plurality.

It will be appreciated that certain features of the invention, whichare, for clarity, described in the context of separate embodiments, mayalso be provided in combination in a single embodiment. Conversely,various features of the invention, which are, for brevity, described inthe context of a single embodiment, may also be provided separately orin any suitable sub-combination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. In addition, citation or identification of anyreference in this application shall not be construed as an admissionthat such reference is available as prior art to the present invention.

1-21. (canceled)
 22. An optical device comprising: (a) an opticalsubstrate; and (b) at least one multi-functional layer, fixedly attachedto an optical surface of said optical substrate; the multi-functionallayer including a plurality of multi-functional areas, eachmulti-functional area of the multi-functional areas including functionaldots containing photochromic colorant, each of said functional dotsfractionally covering said multi-functional area; wherein each saidmulti-functional area is a rectangular area having a contiguous area ofup to 0.04 square millimeters and a short side of at least 20micrometers; said functional dots including: a first group of thefunctional dots, having a first photochromic functionality; and a secondgroup of the functional dots, having a second photochromicfunctionality, said second photochromic functionality having a differingfunctionality from said first photochromic functionality.
 23. Theoptical device of claim 22, wherein said photochromic colorant coversless than 70% of a total surface area of said multi-functional layer.24. The optical device of claim 22, wherein, within each said area ofsaid multi-functional areas, a gap between adjacent functional dotsbelonging to said first and second groups, respectively, is at least 5μm.
 25. The optical device of claim 24, wherein said gap is at most 50μm.
 26. The optical device of claim 25, wherein said gap is an averagegap of at least 25 randomly selected multi-functional areas of saidplurality of multi-functional areas.
 27. The optical device of claim 25,wherein said gap is an average gap between all pairs of said adjacentfunctional dots within an optical field of view image, said imagecontaining at least 10 functional dots.
 28. The optical device of claim25, wherein said photochromic colorant covers less than 70% of a totalsurface area of said multi-functional layer.
 29. The optical device ofclaim 22, wherein said first group and said second group of saidfunctional dots include jetted dots.
 30. An optical device comprising:(a) an optical substrate; and (b) at least one multi-functional layer,fixedly attached to an optical surface of said optical substrate; themulti-functional layer including a plurality of multi-functional areas,each multi-functional area of the multi-functional areas includingfunctional dots containing photochromic colorant, each of saidfunctional dots fractionally covering said multi-functional area;wherein each said multi-functional area is a rectangular area having acontiguous area of up to 0.04 square millimeters and a short side of atleast 20 micrometers; said functional dots including: a first group ofthe functional dots, having a first photochromic functionality; and asecond group of said functional dots, having a second functionality,wherein said second functionality is a differing functionality withrespect to said first photochromic functionality; and wherein disposedbetween said optical substrate and said at least one multi-functionallayer is a layer of anti-wetting material.
 31. The optical device ofclaim 30, wherein said layer of said anti-wetting material is continuouswith respect to said optical substrate.
 32. The optical device of claim30, wherein said multi-functional layer is separated from said opticalsubstrate by a distance of at most 1000 nm.
 33. The optical device ofclaim 31, wherein said multi-functional layer is separated from saidoptical substrate by a distance of at most 1000 nm.
 34. An opticaldevice comprising: (a) an optical substrate; and (b) at least onemulti-functional layer, fixedly attached to an optical surface of saidoptical substrate; said at least one multi-functional layer including aplurality of multi-functional areas, each multi-functional area thereofincluding functional dots containing photochromic colorant, each of thefunctional dots fractionally covering said multi-functional area;wherein each said multi-functional area is a rectangular area having acontiguous area of up to 0.04 square millimeters and a short side of atleast 20 micrometers; the functional dots including: a first group ofthe functional dots, having a first photochromic functionality; and asecond group of the functional dots, having a second functionality, saidsecond functionality having a differing functionality from said firstphotochromic functionality; wherein said optical substrate is a curvedoptical substrate, and wherein said optical surface is a curved opticalsurface.
 35. The optical device of claim 34, said multi-functional layerbeing separated from said optical substrate by a distance of at most1000 nm.
 36. The optical device of claim 34, wherein, within each saidarea of said multi-functional areas, a gap between adjacent functionaldots belonging to said first and second groups, respectively, is atleast 5 μm.
 37. The optical device of claim 36, said gap being at most50 μm.
 38. The optical device of claim 37, said functional dots beingdistributed over a nominal surface area, said functional dots having atotal coverage area, a ratio of said total coverage area to said nominalsurface area being at most 0.65.
 39. The optical device of claim 34,wherein said first and second groups of functional dots have acomposition differing with respect to a composition of said surface ofsaid optical substrate.
 40. The optical device of claim 34, wherein saidfirst and second groups of functional dots include jetted dots.